Complementary Fuse Test Method for Disconnection Failure Detection
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Solution Overview
Problem
Semiconductor devices using fuses as nonvolatile storage elements face challenges in ensuring that fuses are correctly disconnected, as maladjustment of optical energy or irradiation position can lead to unintended disconnections, causing failures where fuses other than the intended ones are disconnected, resulting in unstable output values that may pass shipping tests but later cause issues.
Innovation Solution
A semiconductor device and test method that includes a fuse circuit with complementary fuses, a test voltage application circuit, and a comparison circuit. The method involves applying test voltages to the output terminal of the fuse circuit and determining if the output data coincides with expected values through two successive test sequences, allowing for reliable detection of disconnection failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser light is used to blow the fuse by optical energy, then the fuse can be disconnected, but unintended fuses may also be disconnected due to maladjustment of optical energy or irradiation position
Solution Approach 1:
The patent applies preliminary anti-action by pre-charging the output terminal with a test voltage before reading the fuse state. This preliminary action creates a known initial state that prevents misinterpretation of floating voltages, thereby counteracting the harmful effect of unintended fuse disconnections. The test voltage is applied in advance to ensure that any subsequent voltage reading accurately reflects the actual fuse disconnection state rather than a floating condition.
Solution Approach 2:
The patent implements preliminary action by performing a test voltage application step before the actual fuse state readout. This preliminary test establishes a reference voltage level at the output terminal, ensuring that when the fuse state is subsequently read, the voltage measurement is taken from a known initial condition. This preliminary preparation eliminates the ambiguity caused by floating voltages and enables accurate detection of genuine fuse disconnections.
2Device complexity
If complementary fuse output is read without test voltage application, then the reading process is simple, but the output value becomes floating and unstable when both fuses are disconnected
Solution Approach 1:
The patent applies preliminary action by pre-charging the output terminal with a test voltage before reading the fuse state. This preliminary action creates a known initial state that prevents misinterpretation of floating voltages, thereby counteracting the harmful effect of unintended fuse disconnections. The test voltage is applied in advance to ensure that any subsequent voltage reading accurately reflects the actual fuse disconnection state rather than a floating condition.
3Productivity
If shipping test is performed without test voltage application, then the test can pass with coincidental data matching, but the device may cause problems later when mounted
Solution Approach 1:
The patent applies preliminary action by pre-charging the output terminal with a test voltage before reading the fuse state. This preliminary action creates a known initial state that prevents misinterpretation of floating voltages, thereby counteracting the harmful effect of unintended fuse disconnections. The test voltage is applied in advance to ensure that any subsequent voltage reading accurately reflects the actual fuse disconnection state rather than a floating condition.
Solution Approach 2:
The patent implements feedback by comparing the voltage read from the output terminal against expected values that account for the pre-applied test voltage. This feedback mechanism ensures that the shipping test results accurately reflect the true fuse disconnection state. The comparison step provides verification that the fuse configuration matches the intended design, preventing defective devices from being shipped while maintaining high test efficiency through automated voltage comparison.
Data Source
AI summary
A test voltage having a first voltage or a second voltage is applied to an output terminal of a complementary fuse that includes a first fuse to one end of which the first voltage is applied and the other end of which serves as the output terminal and a second fuse to one end of which the second voltage is applied and the other end of which is connected to the output terminal. The test voltage then stops being applied. In such a state, whether output data from the output terminal of the complementary fuse coincides with an expected value is determined. The result of determination is output as a test result.